Studying fixation probabilities thus became an important aspect of understanding the evolution of collective behaviour. They were studied as functions of the initial number of mutants [1]}, and it has been proved that each of the 8 possible evolutionary scenarios has associated to it one (and only one) of three function shapes. In [2]}, [3]}, they were studied for changing initial number of mutants and intensity of selection under the pairwise comparison process. They have also been extensively studied in the context of structured populations [4]}, [5]}, [6]}, [7]}.
